More than 20 hours after fighters from Somalia's Al Qaeda-linked Shebab group stormed the Westgate complex in an attack that killed at least 39 people and wounded 150 more, security officials said they were still trying to kill or capture the remaining gunmen.

"We are pushing on but it is quiet for now. All our energies are devoted to ending this," a Kenyan Army said.

Large numbers of soldiers in helmets and flak jackets, some carrying rocket-propelled grenades, could be seen headed towards the mall. The Kenyan interior ministry said the upper floors of the four-storey mall had been secured, and that the attackers had been isolated somewhere on the ground floor or in the basement. An unknown number of hostages were also still trapped inside, officials said during the night.

Shebab rebels said the carnage at the part Israeli-owned mall was in direct retaliation for Kenya's military intervention in Somalia, where African Union troops are battling the Islamists.